Check valve?

[Heavenlytunes]

Can anyone tell me what this is and why is necessary?
PB's work looks clean but don't know if is right. It looks right to me
Coming from 18 years AG pool to IG pool and learning as I go along.

 

[ajw22]

It is an automatic high flow bypass valve. HP has a maximum flow rate it can handle. If your flow rate is above that the valve will bypass some water.

 

[Heavenlytunes]

It is an automatic high flow bypass valve. HP has a maximum flow rate it can handle. If your flow rate is above that the valve will bypass some water.

So I'm assuming is a really good add on piece from the PB.
I'm been looking at videos and pictures to see if I see something similar and nothing but in the manual it does show a check valve.

 

[Heavenlytunes]

So is my water always running through the heater? Do I need a bypass valve?

 

[ajw22]

It is a high flow bypass valve, not a check valve. Very different function.

 

[ajw22]

So is my water always running through the heater? Do I need a bypass valve?

Yes.

You have no way to take the heater out of the water loop if it leaks.